Two extremely rare new species of fossorial salamanders of the genus Oedipina (Plethodontidae) from northwestern Ecuador

We describe two new species of salamanders of the genus Oedipina, subgenus Oedopinola, from two localities on the northwestern foothills of Ecuador, at elevations between 921 and 1,067 m. These are the southernmost members of the genus. We examined different museum collections and we found just three specimens of Oedipina from Ecuador, obtained throughout the history of herpetological collections in the country. We identify two of the three specimens as new species, but refrain from assigning a specific identity to the third, pending further study. Oedipina villamizariorum sp. n. is a medium-sized member of the genus, with a narrow, relatively pointed head and blunt snout; dorsolaterally oriented eyes, moderate in size; and digits that are moderately long and having pointed tips. Oedipina ecuatoriana sp. n., somewhat larger, has a narrow head and broadly rounded snout; this new species differs from all known Oedipina by the distinctive presence of paired prefrontal bones and a reduced phalangeal formula: 0-0-1-0; 0-1-2-1-1. We provide detailed descriptions of the osteology of both new species. Finally, we present a phylogenetic hypothesis for the genus, including one of the two new species, based on partial sequences of mitochondrial DNA.

Hyperphalangy in a new sinemydid turtle from the Early Cretaceous Jehol Biota

Hyperphalangy is a rare condition in extant aquatic turtles, and mainly limited to soft-shelled turtles. Here we report a new freshwater turtle,Jeholochelys lingyuanensisgen. et sp. nov. from the Early Cretaceous Jehol Biota of western Liaoning, China. This new turtle is characterized by a hyperphalangy condition with one additional phalanx in pedal digit V, rather than the primitive condition (phalangeal formula: 2-3-3-3-3) of crown turtles.J. lingyuanensisis recovered with other coexisting turtles in the family Sinemydidae in the phylogenetic analysis. This discovery further confirms that hyperphalangy occurred multiple times in the early evolutionary history of the crown turtles. Hyperphalangy is possibly a homoplasy inJeholochelysand the soft-shelled turtles to adapt to the aquatic environments.

Phalangeal formulae and ontogenetic variation of carpal morphology in Testudo horsfieldii and T. hermanni

We compared variation in phalangeal and carpal morphology of the Central Asian Testudo horsfieldii, a burrow-digging tortoise species, with its sister taxon T. hermanni, a Mediterranean species without extensive digging behaviour. Thirty-two Testudo horsfieldii kazachstanica shared the same phalangeal formula (0-2-2-1-1). The distal carpal 1 and metacarpal I as well as the pisiform were consistently lacking, sometimes also the medial centrale. Phalangeal morphology was more variable in Testudo hermanni hermanni. In 29 specimens four phalangeal formulae were found that differed with respect to the reduction of digit 1 (1-2-2-2-1, M-2-2-2-1, D-2-2-2-1, 0-2-2-2-1). The pisiform develops late in ontogeny and is lacking in very most juveniles and subadults. In contrast to T. h. kazachstanica, the medial centrale is always present. In both T. h. kazachstanica and T. h. hermanni carpalia increasingly fuse with age and size. The underlying morphological patterns differ however. The extreme character state in aged T. h. kazachstanica is one large solid bone element, formed by the fused intermedium, ulnare and both centralia. Aged T. h. hermanni have, in contrast, two separate larger carpal elements, one formed by the fused lateral and medial centralia and the other by the fused distal carpalia 1 and 2; the intermedium and ulnare never fuse with one another or with other carpalia. While a partial or complete loss of digit 1 seems to be characteristic for all Testudo species, we propose that the extensive fusion of carpal elements in T. horsfieldii is correlated with its natural history because a rigid manus could be advantageous for burrow-digging. Also the reduction of digit 4 (one phalanx present), a rare character among testudinids and not occurring in other Testudo species, could be linked with its mode of life.

Osteology in the Cuora galbinifrons complex suggests conspecifity of C. bourreti and C. galbinifrons, with notes on shell osteology and phalangeal formulae within the Geoemydidae

Thirty-six complete skeletons, three shells, and x-rays of the extremities of 32 additional turtles of the Cuora galbinifrons complex have been compared with 38 other geoemydid species from 19 genera. Cuora bourreti differs from C. galbinifrons and C. picturata by a lost phalanx in the fourth finger and fourth toe. Individuals with a shell shape intermediate between C. bourreti and C. galbinifrons, as found on Hainan Island (China), have either the reduced phalangeal formula of C. bourreti (manus: 2-3-3-2-2, pes: 2-3-3-2-1) or the complete number of phalanges (manus: 2-3-3-3-2, pes: 2-3-3-3-1). Only in C. flavomarginata did we also register a lost phalanx in the fourth digit of manus and pes; in the pes of C. mouhotii the same character state may occur. In C. flavomarginata the fifth digit of the pes is also lacking. Some other terrestrial and semiterrestrial geoemydids (Cuora mccordi, Heosemys spinosa, and in part C. mouhotii and Leucocephalon yuwonoi) display a similar pattern of phalangeal reduction, resulting in the loss of the fifth digit of the pes. Likewise, in tortoises (Testudinidae), a further group of terrestrial chelonians, and the terrestrial turtle genus Terrapene (Emydidae) the loss of phalanges or complete digits is known to occur. Malayemys subtrijuga, Morenia petersi, Pangshura smithii and Siebenrockiella crassicollis differ from all other studied geoemydid taxa by an additional phalanx in the fifth digit of the manus (2-3-3-3-3); one P. smithii has on one body side three phalanges in the fifth digit of the pes (2-3-3-3-3). These are highly aquatic turtles with extensive toe webbing. Probably, longer digits (and thus a higher phalangeal number) are a favorable prerequisite for swimming while phalangeal loss seems to be the consequence of walking.Cuora bourreti and C. picturata have consistently in the bony carapace a very rare character state regarding the articulation of the rib tips with the peripheral plates. In both species the rib tips are intercalated between two peripheral plates in the bridge region. Intercalated rib tips like those in C. bourreti and C. picturata were found only in C. m. mouhotii, but not in the southern subspecies C. mouhotii obsti. In C. galbinifrons and all other geoemydid taxa studied the rib tips articulate on the bridge within the underlying peripheral and not between two peripherals. In turtles morphologically intermediate between C. bourreti and C. galbinifrons both characters states are found. This suggests that such individuals are hybrids or intergrades. Three known-locality specimens from Hainan Island display both extremes and an intermediate character state. This, together with external morphology and the occurrence of both phalangeal formulae in approximately the same frequency on that island, argues for genetic introgression of C. bourreti on the Hainan population of C. galbinifrons. We conclude that our findings qualify C. galbinifrons and C. bourreti under the Biological Species Concept as conspecific.

Anatomy of the primitive bird Sapeornis chaoyangensis from the Early Cretaceous of Liaoning, China

Two new, nearly completely articulated skeletons of Sapeornis chaoyangensis provide much new information about the anatomy of this basal avian, particularly in the skull, pectoral girdle, forelimb, and hind limb. This new material shows that the hand of Sapeornis, with a phalangeal formula of "2–3–2," was more derived than previously reconstructed. The skeleton of Sapeornis has several unique features, such as a distinctively elongated fenestra on the proximal end of the humerus, a robust furcula with a distinctive hypocleidum, and an elongated forelimb. Sapeornis exhibits a combination of derived and primitive features, including a short, robust non-strut-like coracoid and a fibula reaching the distal end of the tarsal joint (as in Archaeopteryx), a pygostyle, reduced manual digits, and a well-fused carpometacarpus (as in more advanced birds). These features further indicate the mosaic pattern in the early evolution of birds and confirm the basal position of Sapeornis near Archaeopteryx and Jeholornic in the phylogeny of early birds. The preservation of gastroliths in one of the new specimens also represents the first Chinese Mesozoic bird with such evidence, indicating a herbivorous feeding habit and providing further evidence for our understanding of the diet diversification in early avian evolution.

The postcranial skeleton ofDiscosauriscusKuhn, a seymouriamorph tetrapod from the Lower Permian of the Boskovice Furrow (Czech Republic)

The description of the postcranial skeleton of larval, metamorphic and early juvenile specimens of the genusDiscosauriscusis based on three-dimensional material and includes a description of the ontogeny of the swollen neural arches and the central elements of the vertebrae.Discosauriscushas 24 (or 23) presacral vertebrae. The morphology of the atlas–axis complex is similar to that inSeymouria sanjuanensis. The neural arches start to swell slightly in specimens of late larval stage; they are completely swollen immediately after metamorphosis. There are about 40 caudal vertebrae and one sacral vertebra. The atlantal pleurocentrum is paired in metamorphic individuals. In postmetamorphic individuals, the pleurocentra 2–5 are not completely closed dorsally; the pleurocentra 6–30 form complete discs. The first haemal arch is situated on the sixth caudal vertebra. The atlantal rib is present. There are six caudal ribs.Discosauriscushas an anocleithrum which is the first record of this dermal pectoral element within seymouriamorphs and Lower Permian tetrapods. The scapula and the coracoid are separate elements. The phalangeal formula of the manus is 2, 3, 4, 5, 3. The iliac blade has a massive, almost horizontally oriented posterior process; the anterior process is absent. The phalangeal formula of the pes is 2, 3, 4, 5, 3. Rounded ventral scales are present. The comparison and evaluation of the available postcranial elements ofDiscosauriscus, Utegenia, AriekanerpetonandSeymouriasupport the view thatDiscosauriscusandAriekanerpeton, forming the family Discosauriscidae, are immediately related genera.

Westlothiana lizziae from the Viséan of East Kirkton, West Lothian, Scotland, and the amniote stem

ABSTRACTWestlothiana lizziae is known from the Brigantian of East Kirkton, Scotland. The skull resembles that of later amniotes in the large size of the parietal, the apparent loss of the intertemporal, and the absence of a squamosal notch, palatal fangs and labyrinthine infolding of the marginal teeth, but is primitive in the absence of a transverse flange of the pterygoid. The individual trunk vertebrae resemble those of amniotes; large intercentra are retained, but the neural arch is fused to the centrum. A surprising feature is the presence of 36 presacral vertebrae, as is the relative size of the very small but highly ossified limbs. The humerus is much shorter than the femur, but similar in configuration to that of early amniotes. There are three proximal tarsals as in primitive tetrapods, but an amniote phalangeal count. The presence of massive dorsal as well as ventral scales is a more primitive feature than that of most anthracosaurs.Westlothiana is ‘reptiliomorph’, and is judged to be a stem-group amniote on features of the skull roof, the absence of an otic notch, the gastrocentrous vertebrae and the pedal phalangeal formula. It has not, however, reached the amniote condition in the structure of the tarsus, and the palate is more primitive than that of both early amniotes and the ‘diadectomorphs’.

Limb skeletal variation in the Jemez Mountains salamander, Plethodon neomexicanus

We examine limb skeletal variability in Plethodon neomexicanus, a geographically isolated species of plethodontid salamander endemic to the Jemez Mountains of New Mexico, U.S.A. Data are derived from a series of 25 specimens prepared as whole mounts stained for bone and cartilage. Only 25% of hind limbs display the derived hind limb phalangeal formula 1-2-3-3-1, once considered characteristic of this species; two hind limb and one forelimb phalangeal formulae are reported for the first time. In addition, there are six variant carpal and tarsal patterns as well as the two predominant, primitive mesopodial patterns that are typical of most other species of Plethodon as well as of many other plethodontid genera. Limb skeletal variability in P. neomexicanus is among the highest recorded for urodeles and may represent an ancient and widespread polymorphism in the genus Plethodon.